The present invention relates to a method of treating a continuous web of wood or cellulose pulp produced in a dewatering apparatus such as a suction mould and having a relatively high content of water.
The invention also relates to an apparatus for carrying out the method.
There is previously known a method of treating wood or cellulose pulp, in which the pulp leaving a suction mould in the form of a continuous web having a solids content of approximately 25 weight percent is passed directly into subsequent pressing means having the same operating width as the suction mould. In such a method the pulp web is freely suspended between the suction mould and the first pressing means and between the various pressing means. Thus, a required tensioning of the web is achieved, which counteracts a skew pulling of the web in the pressing means. If the web is made of cellulose mass, which forms a stronger web than a wood pulp, the web may be tensioned by means of a transverse roller resting on the web. After the pulp web has passed the pressing means, including grooved rollers, it may, for example, have a solids content of approximately 50 percent depending on the number of pressing sections it has gone through and the pressing pressure at which the rollers have been set. Then the web is slitted longitudinally in two or more narrower pulp webs which thereupon are placed on top of each other and severed transversely into suitable sheet sizes. These sheet layers are then stacked into suitable heights for later bundling in bales which may either be stored or conveyed to paper plants in which the pulp is subsequently ground and treated in paper machines.
The previously known method is encumbered with some disadvantages. Firstly, it requires a great operating staff, the starting up of the process requiring three operators. One operator must control the speed and two must carry out the threading of the pulp web through the machine. Due to the relatively large width of the web, a skew pulling of the web concurring rupture thereof during the threading operation may easily occur, requiring another threading of the web in the machine and, accordingly, loss of production time. The large width of the web also requires large pressing means, and the rollers which perform the pressing operation, must be of a robust design having a larger diameter in the middle area due to deformation, and having bearings which must withstand high loads.